Q.What should I be cautious of when connecting multiple units in series?

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A. When connecting multiple units in series, high voltage is applied between the power supply output (secondary side) and the FG. Therefore, it is necessary to consider isolation between the power supply output and the FG.
Based on consideration of customer equipment, basic isolation is required between the power supply output and the FG.
Furthermore, if there is an SELV (ES1 in 62368-1) part in customer equipment, reinforced isolation is required between the SELV (ES1 in 62368-1) and the power source output. Also, reinforced/double isolation may be necessary for the output line.
Additionally, if the output voltage exceeds 60V DC, which is the upper limit of the SELV (ES1 for 62368-1) target range, it is also necessary to prevent the electric shock which will result when touching the human body, etc.
Also, the output voltage in series operation and the withstand voltage for the required isolation change depending on the conditions of customer equipment.
Please contact TDK-Lambda for details.
TDK-Lambda products are designed with SELV (ES1 of 62368-1) and the target range is 60V DC or less.
If the power supply outputs are connected in series that does not exceed SELV (ES1 in 62368-1), the safety standards for a "single power unit" take effect.